Electric heater



June 26, 1962 w. E. BAKER 3,041,567

ELECTRIC HEATER Filed March 14, 1960 2 Sheets-Sheet 1 FIG. 3

INVENTOR WILLIAM EDWIN BAKER HIS 'ATTQRNEY June 26, 1962 w. E. BAKER 3,041,567

ELECTRIC HEATER Filed March 14, 1960 2 Sheets-Sheet 2 INVENTOR WILLIAM EDWIN BAKER M X QM HIS ATTORNEY United States Patent Oflice 3,041,567 Patented June 26, 1962 3,041,567 ELECTRIC HEATER William Edwin Baker, Needham, Mass, assignor to Standard Thomson Corporation, Waltham, Mass., at corporation of Delaware Filed Mar. 14, 1960, Ser. No. 14,954 6 Claims. (Cl. 338-63) This invention relates to an actuator assembly. The invention relates more particularly to an electrically controlled actuator assembly.

This application relates to the copending E. J. Kimm application Serial Number 519,564, filed July 1, 1955, now Patent No. 2,928,233, issued March 15, 1960, and having the same assignee as the assignee of this application.

An object of this invention is to provide an electrically controlled actuator assembly which is capable of producing very large values of power in consideration of its physical size.

Another object of this invention is to provide such an electrically controlled actuator assembly which is capable of rapid rates of response.

Another object of this invention is to provide such an electrically controlled actuator assembly which is extremely accurate in operation.

Another object of this invention is to provide a heater unit which is capable of rapid and uniform diffusion of heat.

Another object of this invention is to provide a heater unit which is durable, rigid, and long lived.

Another object of this invention is to provide a method of producing such a heater unit at comparatively low costs.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture, and the mode of operation, as will become more apparent from the following description.

In the drawing:

FIGURE 1 is a sectional View, with parts broken away, of an electrically controlled actuator assembly of this invention.

FIGURE 2 is a view taken substantially on line 22 of FIGURE 1.

FIGURE 3 is an enlarged sectional view of a portion of the assembly as shown in FIGURE 1.

FIGURE 4 is a plan view of one of the first steps in a method of producing a heater unit of this invention.

FIGURE 5 is a plan view showing another step in the method of producing a heater unit of this invention.

FIGURE 6 is an enlarged plan view, with parts broken away and shown in section, illustrating another step in the method of producing a heater unit.

FIGURE 7 is an elevational view showing a heater unit of this invention.

Referring to the drawings in detail, an actuator assembly of this invention comprises a container 28, best shown in FIGURE 1, provided with an end wall or end cover 22. Extending through the end wall 22 is actuator means in the form of a rod 24 which is axially reciprocally movable with respect to the end wall 22.

Within the container 20 is an elastic body or sealing member 26. The elastic sealing member 26 may be a rubber or an elastomeric or other suitable rubber-like material. The elastic sealing member is shown as having a flange 28 which is in engagement with the end wall 22. The elastic sealing member 26 may also have a neck portion 30 which extends through the end wall 22 along the surface of the rod 24.

Also within the container 20 is a body of thermal expansive work producing material 34 which may be any suitable composition which has a high coeflicient of expansion over a desired temperature range. A silicone oil has been found to be satisfactory. However, other compositions have also been found satisfactory. The thermal expansion material 34 engages the exterior surface of the sealing member 26 while the rod 24 engages the interior surface of the sealing member 26.

A heater unit 40 is disposed Within the thermal responsive material 34. The heater unit 40 comprises a suitable foil and heat producing means. The heater unit is constructed as follows: A strip of metallic foil 44, such as aluminum or the like, of suitable width and length is laid out flat, as shown in FIGURE 4. Then an electrically insulated heater wire 46 is doubled and laid substantially diagonally upon the foil 44, as shown in FIG- URE 4. The two ends of the heater wire 46 extend slightly from the foil 44 adjacent one corner thereof. The doubled end portion of the heater wire 46 is adjacent a diagonally opposite corner of the strip of foil 44.

Then the end of the strip of foil 44 which is adjacent the doubled end of the heater wire 46 is folded over upon the heater wire 46, as shown at the left portion of FIGURE 4. Then the strip of foil 44, with the heater wire 46, is tightly wound upon any suitable mandrel 50, as shown in FIGURE 5. FIGURE 6 shows a fragmentary sectional view of the strip of foil 44 and the heater wire 46 as they appear in a partially wound condition.

Due to the fact that the foil 44 is very thin and pliable,

tight winding together of the foil 44 and the heater wire 46 causes distortion of the foil as the convolutions of the heater wire form bulges in the foil 44, as best shown in FIGURES 5, 6, and 7. The heater wire 46 thus adds rigidity to the foil 44 as the heater wire 46 is evenly distributed throughout the foil 44. The heater wire 46 is thus placed in excellent thermal transfer relation with the foil 44.

After the strip of foil 44 and the heater wire 46 are completely wound as an assembly, a flexible roller may be pressed against the assembly While it is rotating. This operation serves to form the metal foil 44 into more intimate contact with the heater wire 46. After this operation is completed, the mandrel 50 is removed and the heater unit 40 appears as shown in FIGURE 7. Any suitable means are employed to retain the foil 44 and the heater wire 46 in a tightly wound coil so that the coil does not unwind. The heater unit 40 is disposed within the thermal responsive material 34 within the container 20. A pair of connection posts 52 extend through the end wall 22, as best shown in FIGURES l and 3. An insulating sleeve 54 electrically separates each connection post 52 from the end wall 22. Each connection post 52 has a flange 56 within the container 20. The flange 56 of each post 52 is in engagement with the flange 28 of the sealing member 26 as the connection posts 52 extend through the flange 28.

Each post 52 has an inner end 58 of reduced crosssection which is joined to one end of the heater wire 46 by means of an adapter 60. A portion of each post 52 is threaded and a nut 62 firmly attaches the post to the end wall 22. Each nut 62 engages a washer portion 64 of the sleeve 54 which encircles its respective post 52. Encircling the inner end 58 of each post 52 is an insulator sleeve 66 which also encompasses the adapter 60 which is connected to the inner end 58. Each sleeve 66 extends between its respective post 52 and the heater unit 40.

Any suitable source of energy can be connected to the connection posts 52 for energization of the heater wire 46. When the heater wire 46 is energized, heat therefrom rapidly flows into the foil 44 from which the heat is readily dissipated and distributed into the thermal responsive material 34. When the thermal responsive material 34 is heated, expansion thereof occurs. This expansion causes squeezing upon the sealing member 26 which results in movement of the actuator rod 24 in a direction outwardly from the container 20. Thus, energization of the heater unit 40 results in operation of the actuator rod 24.

The actuator rod 24 can move in a direction into the container 20 after the heater unit has been deenerg-ized so that the thermal responsive material 34 contracts.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable ofcarrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. A heater unit comprising an elongate strip of metallic foil having a pair of opposite end portions, an insulated heater wire provided with a doubled end portion at one end portion of the strip of metallic foil, the wire having two parallel portions extending directly between opposite end portions of the strip of metallic foil, the strip of metallic foil and the heater wire being tightly wound together into a plurality of helical convolutions sothat the doubled heater wire is in the form of a helix with the convo'lutions thereof within the helix formedby the strip of metallic foil.

2. A heater unit particularly adapted for use with a thermally responsive actuator comprising a strip of metallic foil, an insulated heater wire which has a length approximately twice the length of the strip of metallic foil, the heater wire being doubled and placed in engagement with the strip of metal foil so that the wire extends substantially the length of the strip of metallic foil, there being a doubled portion of the wire adjacent one end of the strip of metallic foil with the two ends of the wire adjacent the opposite end of the strip of metallic foil, the wire and the strip of metallic foil being in the form of a tightly wound helical coil with said two ends of the wire extending from the coil.

3. A heater unit comprising a substantially rectangular strip of metallic foil material, an insulated electric wire in engagement with the strip of foil material, the wire being of a length which is substantially twice the length of the strip of metallic foil material, the wirehaving a doubled portion adjacent one end of the strip of metallic foil material and adjacent a corner thereof, the wire having two end portions extending from the opposite end portion of the strip of foil material and adjacent a corner which is opposite the first said corner of the strip of foil material, the strip of foil material and the wire being in the form of a tightly wound helical coil, with the surface of the strip of metallic foil being distorted as the strip of metallic foil is longitudinally partially wrapped around the wire, there thus being intimate contact between the strip of foil material and the wire.

4. A heater element for a thermal responsive actuator comprising a strip of metallic foil, a heater wire, the heater wire having a length approximately equal to two times the length of the strip of metallic foil, the heater wire being doubled and extending diagonally across the length of the strip of metallic foil and in firm engagement therewith, the strip of metallic foil and the heater wire being in the form of a helical coil.

5. The method of producing a heater unit comprising forming a sheet of metallic foil mataerial into a substantially rectangular elongate strip, followed by placing a doubled elongate heater wire diagonally upon the strip so that a doubled end portion of the wire is adjacent one corner portion of the strip and so that both ends of the heater wire extend from a diagonally opposed corner portion of the strip, followed by tightly rolling the strip into a helical coil with the heater wire firmly disposed between adjacent convolutions of the strip so that an elongate helical coil is formed by the heater wire as the heater wire is distributed throughout the axial length of the helical coil formed by the metallic foil.

6. A heater unit comprising a helical coil of metallic foil material, the coil of foil material including an elongate substantially rectangular strip, a doubled heater wire in helical form within the helical coil of foil material, the heater wire having a single doubled portion, the heater wire being positioned diagonally in contact with the elongate strip of foil material so that the Wire extends from one corner portion of the strip to a diagonally opposite corner portion of the strip, the convolutions of the helical coil of foil material being in tight engagement so that the heater wire is in tight engagement with the convolutions of the :foil material and so that'the heater wire is in the form of an elongate helix distributed through the convolutions of the foil material.

References Cited in the file of this patent UNITED STATES PATENTS 1,674,488 Tang June 19, 1928' 2,271,307 Ray Jan. 27, 1942 2,348,462 Framburg et al. May 9, 1944 2,409,112 Dillman Oct. 8, 1946 2,412,843 Spraragen Dec. 17, 1946 2,582,341 Levers et al. Jan. 15, 1952 2,589,614 Ireland Mar. 18, 1952 2,655,582 Kirby Oct. 13, 1953 2,745,942 Cohen May 15, 1956 2,809,268 Heron Oct. 8, 1957 2,833,507 Dube et al. May 6, 1958 2,928,233 Kimm Mar. 15, 1960 2,941,379 Nelson June 21, 1960 2,952,001 Morey Sept. 6', 1960 

